I was actually refering to other female hybrids, not Renesmee-I assume that she might never produce venom on her own, though when she matures she can produce venom possibly, but that's not known nor has been satisfactorily explained, like many traits of Nessie or other hybrids.
As for Bella becoming a hybrid for some reason after Nessie matures, I know that it's not likely because as far is known in the canon of the story, and the science is part of that canon, that there's really no known ways for full vampirism to be reversed, at least one that's natural in nature, but Bella is unique in that she's the only person to survive a vampire-hybrid birth, and I thought that some mechanism to turn her into a hybrid when Nessie's older.
Besides, Bella and Edward influenced Renesmee and her gifts, so why can't she, in a way, give something back to the one she loves most(her mother)? And Edward would probably like it if Bella was a hybrid, because she'd be half human, and some of her human traits(like eye color, and her skin having some color and being able to blend in with people) could come back, but her clumsiness wouldn't and she'd keep most if not all her vampire ablities.
That, and I think that the hybrids are cool, and I think that Bella would like to feel what it would be like to be like her daughter in that respect.
Canon wise, I doubt that Bella becoming a hybrid will work because they're might not be a satisfactory explanation, but in the world of fan fiction, as there, at least for the foreseeable future, is no plans for more new Twilight Saga material from Stephenie aside from maybe explaining some characters though short stories(like Bree), it can be possible, because the future from that stand point is wide open.
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Fan fic stories: http://www.fanfiction.net/u/2192109/